Abaixo está uma instrução que descreve uma tarefa de geração de SQL, combinada com uma entrada que fornece mais contexto sobre os esquemas de tabela disponíveis. Escreva o código SQL que responda adequadamente à solicitação
 ###Instrução: Qual outro candidato concorreu contra Dave Treen?
 ###Tabelas: CREATE TABLE round_21 (round_21_id AUTO_INCREMENT PRIMARY KEY, Home team VARCHAR, Home team score VARCHAR, Away team VARCHAR, Away team score VARCHAR, Venue VARCHAR, Crowd INT, Date VARCHAR) CREATE TABLE doubles:_11_8–3 (doubles:_11_8–3_id AUTO_INCREMENT PRIMARY KEY, Outcome VARCHAR, Date VARCHAR, Tournament VARCHAR, Surface VARCHAR, Partner VARCHAR, Opponents in the final VARCHAR, Score in the final VARCHAR) CREATE TABLE regular_conflicts (regular_conflicts_id AUTO_INCREMENT PRIMARY KEY, Military deaths VARCHAR, Civilian deaths VARCHAR, Total deaths (not including foreigners) VARCHAR, Military and/or Civilian wounded VARCHAR, Total casualties VARCHAR) CREATE TABLE  (_id AUTO_INCREMENT PRIMARY KEY, District VARCHAR, Incumbent VARCHAR, Party VARCHAR, First elected INT, Result VARCHAR, Candidates VARCHAR) CREATE TABLE 2010: (2010:_id AUTO_INCREMENT PRIMARY KEY, Episode VARCHAR, Theme / Date VARCHAR, Song title VARCHAR, Original performer VARCHAR, Result (Placement) VARCHAR)  
SELECT Candidates FROM  WHERE Incumbent = Dave Treen